Cell Structure Flashcards
What is the function of the Vacuole?
- To keep the cell turgid
- Membrane bound sac to store organic and inorganic substances as well as waste
What are the 4 main features of the vacuole?
- Tonoplast
- High hydrostatic pressure
- Coloured pigments
- Large volume
What is the function of the tonoplast within a vacuole?
- Control entry/ exit of substances
- Compartmentalisation
What is the function of having a high hydrostatic pressure within a vacuole?
- For turgidity
What is the function of coloured pigments within a vacuole?
- To attract insects for pollination
What is the function of a large area within a vacuole?
- To push the chloroplasts to the outer edges for maximised CO2 and light absorption
What is the function of the cellulose cell wall?
- Strength and rigidity
- Fully permeable to solutes
What are the 4 main features of a cellulose cell wall?
- Strong composite structure of cellulose microfibrils within a pectin matrix
- Permeable network of cellulose microfibrils
- Middle lamella made of pectin
- Pits and Plasmodesmata
What is the function of a strong composite structure of cellulose microfibrils within a pectin matrix in the cell wall?
- To give the cell strength when it is turgid
What is the function of a permeable network of cellulose microfibrils in the cell wall?
- Allow substances to easily pass through
What is the function of a middle lamella made of pectin within the cell wall?
- To hold cells together
What is the function of the pits and plasmodesmata in a cell wall?
- To allow substances to move easily from cell to cell
What is the function of an amyloplast?
- To store glucose as an insoluble carbohydrate so it can be hydrolysed back to glucose when required
What are the 3 main features of an amyloplast?
- Insoluble starch
- Easy to hydrolyse
- Compact structure
What are the 2 reasons starch is insoluble within an amyloplast?
- So it doesn’t affect osmosis
- So a store is able to be maintained without leaving the cell
Why is the insoluble starch easy to hydrolyse in an amyloplast?
- So it can be converted to glucose when needed for reactions like cell wall synthesis, respiration.
Why does the amyloplast have a compact structure?
- So lots of carbohydrates/ glucose is able to be stored in a small space
What is the function of a chloroplast?
- To absorb light in photosynthesis for glucose
What are the 4 main features of a chloroplast?
- Contain enzymes in the stroma
- Contain ribosomes and DNA in the stroma
- Stacks of thylakoid membranes in the grana
- Double membrane
What is the function of having DNA and ribosomes in the stroma of a choroplast?
- So it can perform protein synthesis independent from the rest of the cell
What is the function of having enzymes within the stroma of a chloroplast?
- To catalyse the many photosynthesis reactions
What is the function of the stacks of thylakoid membranes in the grana of a chloroplast?
- Large SA for chloroplasts and therefore photosynthesis
Why does a chloroplast have a double membrane?
- Compartmentalisation
What is the function of the mitochondria?
- Aerobic respiration
- Release energy from glucose for ATP
What are the 4 main features of the mitochondria?
- Cristae
- Matrix
- DNA and ribosomes
- Double membrane
What is the function of a cristae within the mitochondrion?
- Large SA with enzymes for ATP production
What is the function of the matrix within the mitochondrion?
- Contain enzymes
- Contain the mitochondria’s DNA
What is the function of the DNA and ribosomes within a mitochondrion?
- To perform protein synthesis independent from the rest of the cell
Why does the mitochondria have a double membrane?
- Control the entry/ exit of substances
- Compartmentalisation
What is the function of the Golgi apparatus?
- To modify, tag and package polypeptides into new proteins
What are the 4 main features of the Golgi apparatus?
- Membrane bound cavities
- Enzymes within the cavities
- Form Secretory vesicles
- Lysosomes
What is the function of the membrane bound cavities in the Golgi?
- Compartmentalisation
What is the function of the enzymes within the cavities in the Golgi?
- To catalyse the reactions
What is the function of the secretory vesicles in the Golgi?
- To transport newly formed proteins out of the cell
What is the function of the lysosomes released by the Golgi?
- To break down and destroy old worn out cells with lysozymes (hydrolytic enzymes)
What is the function of the smooth endoplasmic reticulum?
- To synthesise, store and transport lipids
What is the function of the rough endoplasmic reticulum?
- Protein synthesis
What are the 4 main features of the RER?
- Cisternae
- Large SA
- Form vesicles
- Ribosomes
What is the function of the cisternae in the RER?
- Compartmentalisation
What is the function of the large SA within the RER?
- Millions of attachment points for ribosomes for protein synthesis
What is the function of the ribosomes in the RER?
- Protein synthesis
What is the function of the vesicles formed by the RER?
- To transport polypeptides to the Golgi apparatus
What is the function of the nucleus?
- To produce ribosomes
- To store genetic information
- To release polypeptides for modification at the Golgi
What are the 5 main features of the nucleus?
- Nuclear pores
- Nucleolus
- Nuclear envelope
- Chromatin
- Nucleoplasm
What is the function of nuclear pores in the nucleus?
- Control entry/ exit of substances
What is the function of the nucleolus in the nucleus?
- Contain the genes that code for ribosomes
What is the function of the nuclear envelope in the nucleus?
- Compartmentalisation
- Control entry/ exit of substances
What is the function of the chromatin in the nucleus?
- Allow the genes to be read
What is the function of the nucleoplasm in the nucleus?
- Site of reactions
What are the size of ribosomes in eukaryotes?
- 80S
What are the size of ribosomes in prokaryotes?
- 70S
What are the features/ functions of fungal cells?
- Contain most of the organelles found in plant cells
- Contain chitin in the cell wall rather than cellulose
- Don’t contain chloroplasts
What are the features/ functions of algal cells?
- Contain the same organelles as plant cells
- Chloroplasts are a different shape
What are the differences between eukaryotic cells and prokaryotic cells?
- Eukaryotic cells contain a nucleus, prokaryotic don’t.
- Eukaryotic ribosomes are larger than prokaryotic ribosomes.
- Eukaryotic cells are larger than prokaryotic cells.
- Cell wall is made of murein in prokaryotic cells, but cellulose or chitin in eukaryotic cells.
What are some features in prokaryotic cells that are not found in eukaryotic cells?
- Capsule
- Flagellum
- Pili
What is the function of the capsule in prokaryotic cells?
- Protects the cell from attacks from antibiotics or white blood cells
What is the function of the flagellum in prokaryotic cells?
- To propel the cell through the environment
What is the function of the pili in prokaryotic cells?
- To attach the cell onto other surfaces or cells
What are the features of a virus?
- Genetic material
- Glycoproteins
- Capsid
- Envelope
- Enzymes
What type of genetic material is found in a virus?
- DNA or RNA, both single or double stranded
What is the function of the capsid in a virus?
- To protect the genetic material
What is the function of the glycoproteins in a virus?
- To help the virus bind to host cells
What is the function of the enzymes that are sometimes carried in a virus?
- To convert RNA into DNA
What is the maximum resolution and magnification of a light microscope?
Resolution - 0.2 micrometres
Magnification - x1500
What is the difference between transmission and scanning electron microscopes?
- SEM see in 3D, TEM in 2D.
- SEM have a resolution of 5 nm, TEM a resolution of 0.5 nm.
What is the maximum resolution and magnification of an TEM microscope?
Magnification - x1,500,000
Resolution - 0.5 nm
What is the maximum resolution and magnification of an SEM microscope?
Magnification - x1,500,000
Resolution - 5 nm
What are the 3 steps of cell fractionation?
- Homogenisation
- Filtration
- Ultracentrifugation
Why does the sample have to be ice-cold?
- To slow down enzyme activity
Why does the sample have to be isotonic?
- So the water potential isn’t affected
Why does the sample have to be buffered?
- To keep the pH constant
- Prevent the enzymes from denaturing
What is the pellet?
- The sediment at the bottom of the tube, most dense and heaviest.
What is the supernatant?
- The liquid remaining above the pellet
What is the order of organelles from heaviest to lightest in ultracentrifugation?
- Nuclei
- Chloroplast
- Mitochondria
- Lysosomes
- Endoplasmic reticulum
- Ribosomes
What increases the rate of movement across membranes?
- microvilli - increased surface area for the insertion of carrier proteins which diffusion, facilitated diffusion and active transport can take place
- the number of protein channels and carrier proteins in any given area of a membrane